It's okay. – Add Music to Video Editor Review

There is a limited amount of stock music. If you choose to use the stock music and post your video on YouTube (even after paying for the full version), they will put copyright claims on your video so they can run adds on it. They'll let you buy the music, use it, but you do not have license to use it anywhere public. Seems a little backwards to me since I paid for it. The only plus side is that you can use your albums on your phone.
Review by CollinVVV on Add Music to Video Editor.